PRELIMINARY EVALUATION OF THE ROCK-MASS DISTURBANCE RESULTING FROM SHAFT, TUNNEL, OR BOREHOLE EXCAVATION

The isolation of nuclear wastes in deep, mined repositories will require the sealing of all penetrations such as shafts, tunnels, or boreholes, into or nearby the repository. An important consideration in penetration sealing is the disturbed zone, or zone of increased permeability, which may be created in the rock mass adjacent to the penetration as a result of excavation. Disturbed zone characteristics for shafts, tunnels, and boreholes are evaluated by analysis and by review of previous laboratory and field tests. Consideration is given also to test methods for characterizing the disturbed zone in situ, and to methods for treating the disturbed zone in seal construction. Laboratory tests indicate that the disturbed zone associated with small-diameter boreholes is probably insignificant. In contrast, the disturbed zone is potentially a significant pathway for flow through seals placed in shafts and tunnels. Because a major mechanism for disturbance is believed to be stress relief acting across fractures, much of the disturbance occurs regardless of the excavation method used. Various test methods are proposed for disturbed zone characterization in shafts and tunnels, with seismic refraction identified as a promising index test. A proposed method for treating the disturbed zone uses cutoffs constructed as a series of overlapping boreholes. Each hole is filled with concrete which is allowed to cure before the adjacent holes are drilled.

• Corporate Authors:

  D'Appolonia Consulting Engineers, Incorporated

  Albuquerque, NM  United States 

  Department of Energy

  1000 Independence Avenue, SW
  Washington, DC  United States  20585
• Authors:
  • Kelsall, P C
  • Case, J B
  • Chabannes, C R
• Publication Date: 1982-11

Media Info

• Pagination: 154 p.

Subject/Index Terms

• TRT Terms: Excavation and tunneling; Fracture mechanics; Geological events; Physical properties; Refraction; Rocks; Sealing (Technology); Seismicity; Tunneling
• Uncontrolled Terms: Seismic refraction
• Old TRIS Terms: Geological conditions; Rock properties; Rock tunneling; Sealing
• Subject Areas: Bridges and other structures; Construction; Geotechnology; Public Transportation;

Filing Info

• Accession Number: 00378631
• Record Type: Publication
• Report/Paper Numbers: ONWI-411
• Contract Numbers: AC06-76RL01830
• Files: TRIS
• Created Date: Oct 30 1983 12:00AM